In this post, we will discuss Terraform features. The Terraform language includes a number of built-in functions that you can call from expressions to transform and combine values. The general syntax for function calls is the name of the function, followed by the arguments, separated by commas, in parentheses.
<function_name>(<argument1>, <argument2>, …<argumentN>)
Next, we're going to explain Terraform's features with examples. We will be using the terraform console for this demo.
Terraform features:
Open the terraform console
terraform console
Numeric functions
abs(number): .
abs(-19.86)
# 19.86
ceil(number): ,
ceil(7.1)
# 8
floor(number): ,
floor(7.1)
# 7
log(number, base): log .
log(16,2)
# 4
max(N1,N2,..Nn): .
max(3,2,6,8.8,7)
# 8.8
min(N1,N2,..Nn): .
min(3,2,6,8.8,7)
# 2
pow(number,power): , .
pow(8,2)
# 64
signum(number): , -1 1 .
signum(-4)
# -1
signum(4)
# 1
chomp("string"): .
chomp("cloudaffaire\n")
# cloudaffaire
(** \ n )
format(spec, values...):
format("Welcome, to %s", "CloudAffaire")
# Welcome, to CloudAffaire
format("The year is %d", 2019)
# The year is 2019
format("%4.4f+", 3.86)
# 3.8600+
formatlist(spec, values...): formatlist
. , .
formatlist("www.%s.com",list("azure","aws","google"))
# [www.azure.com,www.aws.com,www.google.com]
indent(num_spaces, string): , , .
indent(8,"hi, \n welcome \n to \n cloudaffaire")
#1st line hi has no indentaton
join(separator, list): , .
join(".",list("www","google","com"))
# www.google.com
lower(string): .
lower("CLOUDAFFAIRE")
# cloudaffaire
upper(string): .
upper("cloudaffaire")
# CLOUDAFFAIRE
replace(string, substring, replacement): ,
.
replace("www.google.com","google","cloudaffaire")
# www.cloudaffaire.com
split(separator, string): , .
split(".","www.google.com")
# ["www","google","com"]
strrev(string): . , Unicode.
strrev("google")
#: elgoog
( terraform 0.12 )
substr(string, offset, length): .
substr("www.google.com",4,6)
# google
title(string): .
title("welcome to cloudaffaire")
# Welcome To Cloudaffaire
trimspace(string): .
trimspace(" hello, all ")
# "hello, all
"
chunklist(list, chunk_size): , .
chunklist(list("a","b","c","d","e","f"),3)
# [["a","b","c"],["d","e","f"]]
coalesce(strings\numbers): , .
coalesce("",1,"a")
# 1
coalescelist(list1, list2,… listn): .
coalescelist(list(),list("a","b","c"),list("d","e"))
# ["a","b","c",]
compact(list(string)): .
compact(list("a","","c","","d"))
# ["a","c","d"]
concat(list1, list2,… listn): .
concat(list("a","b"),list("c","d"),list("e","f"))
# ["a","b","c","d","e","f"]
contains(list, value): , .
contains(list("a","b","c"),"a")
# true
contains(list("a","b","c"),"d")
# false
distinct(list): .
distinct(list("a","b","b","c"))
# ["a","b","c",]
element(list, index): .
element(list("a","b","c"),2)
# c #index start from 0
index(list, value): .
index(list("a","b","c"),"b")
# 1
flatten(list(list1,list2,..,listn)): , .
flatten(list(list("a","b"),list("c"),list(),list("d","e")))
# ["a","b","c","d","e",]
keys(map): , .
keys(map("name","debjeet","sex","male"))
# ["name","sex",]
length(list\map\string): , .
length(list("a","b"))
# 2
length("debjeet")
# 7
length(map("name","debjeet","sex","male"))
# 2
list(): , .
list("a","b","c")
# ["a","b","c",]
lookup(map, key, default): , . , .
lookup(map("name","debjeet","sex","male"),"sex","not found!")
# male
lookup(map("name","debjeet","","male"),"gender","not found!")
# not found!
map("key1","value1","key2","value2",...,"keyn","valuen"): ,
.
map("name","debjeet","sex","male")
# {"name" = "debjeet" "sex" = "male"}
matchkeys(valueslist, keyslist, searchset): , ,
.
matchkeys(list("a","b","c"),list("one","two","three"),list("two"))
# b
matchkeys(list("a","b","c"),list("one","two","three"),list("one"))
# a
matchkeys(list("a","b","c"),list("one","two","three"),list("three"))
# c
merge(map1,map2,..,mapn):
.
merge(map("a","one"),map("b","two"),map("c","three"))
# {"a" = "one" "b" = "two" "c" = "three"}
reverse(list): .
, , .
reverse(list("a","b","c"))
#: ["c","b","a",]
( terraform 0.12 )
setintersection(sets...): , , .
setintersection(list("a","b"),list("b","c"),list("b","d"))
# ["b",]
( terraform 0.12 )
setproduct(sets...): , .
setproduct(list("a","b"),list("c","d"))
# [["a","c"],["a","d"],["b","c"],["b","d"],]
( terraform 0.12 )
setunion(sets...): , .
, .
setunion(list("a","b"),list("c","d"))
# ["a","b","c","d",]
( terraform 0.12 )
slice(list, startindex, endindex):
slice(list("zero","one","two","three"),1,3)
# ["one","two"]
sort(list): , .
sort(list("d","c","a","b"))
# ["a","b","c","d",]
transpose(): , .
transpose(map("a",list("one","two"),"b",list("three","four")))
# {"four"=["b",] "one"=["a",] "three"=["b",] "two"=["a",]}
values(map): , .
values(map("name","debjeet","sex","male"))
# ["debjeet","male",]
zipmap(keyslist, valueslist): .
zipmap(list("name","sex"),list("debjeet","male"))
# {"name" = "debjeet" "sex" = "male"}
base64encode(string): Base64 .
base64encode("cloudaffaire")
# Y2xvdWRhZmZhaXJl
base64gzip(string): gzip, Base64.
base64gzip("cloudaffaire")
# H4sIAAAAAAAA/0rOyS9NSUxLS8wsSgUAAAD//wEAAP//38z9sQwAAAA=
base64decode(string): , Base64, .
base64decode("Y2xvdWRhZmZhaXJl")
# cloudaffaire
csvdecode(string): , CSV, , .
csvdecode("a,b,c\n1,2,3\n")
# [{"a"="1" "b"="2" "c"="3"},]
( terraform 0.12 )
jsonencode(): , JSON.
jsonencode(map("name","debjeet"))
# {"name":"debjeet"}
jsondecode(): JSON, .
jsondecode("{\"name\":\"debjeet\"}")
# {"name" = "debjeet"} ( terraform 0.12 )
urlencode(): URL .
urlencode("https://cloudaffaire.com/?s=terraform")
# https%3A%2F%2Fcloudaffaire.com%2F%3Fs%3Dterraform
dirname(string): , , .
dirname("/home/ec2-user/terraform/main.tf")
# /home/ec2-user/terraform
pathexpand(): , ~,
, .
pathexpand("~/.ssh/id_rsa")
# /home/ec2-user/.ssh/id_rsa
basename(string): , , , .
basename("/home/ec2-user/terraform/main.tf")
# main.tf
file(path):
file("/home/ec2-user/terraform/main.tf")
# content of main.tf
fileexists(path): , .
fileexists("/home/ec2-user/terraform/main.tf")
# true if main.tf exist
( terraform 0.12 )
filebase64(path): base64.
filebase64("/home/ec2-user/terraform/main.tf")
# main.tf base64. ( terraform 0.12 )
templatefile(path, vars): , .
formatdate(spec, timestamp): .
formatdate("MMM DD, YYYY", "2018-01-02T23:12:01Z")
# Jan 02, 2018
( terraform 0.12 ). https://www.terraform.io/docs/configuration/functions/formatdate.html
timeadd(timestamp, duration): , .
— , , «1,5 » «1 30 ».
: "ns", "us" (or "µs"), "ms", "s", "m", and "h".
, , "-2h5m".
timeadd("2019-05-10T00:00:00Z", "10m")
# 2019-05-10T00:10:00Z
timestamp():
timestamp()
IP
cidrhost(prefix, hostnum): IP- IP- .
cidrhost("10.0.0.0/16", 4)
# 10.0.0.4
cidrhost("10.0.0.0/16", -4)`` #
10.0.255.252`
cidrnetmask(prefix): IPv4-, CIDR, .
cidrnetmask("10.0.0.0/16")
# 255.255.0.0
cidrnetmask("10.0.0.0/24")
# 255.255.255.0
cidrsubnet(prefix, newbits, netnum): cidrsubnet IP- .
CIDR
newbits
— , .
netnum
— , , newbits
cidrsubnet("10.0.0.0/16",8,2)
# 10.0.2.0/24
cidrsubnet("10.0.0.0/24",8,1)
# 10.0.0.1/32
Exit terraform console
exit
For a complete list of terraform functions, see the terraform documentation below.